2-((2-Ethoxyethyl)(2-hydroxyethyl)amino)-1,3,2-oxazaphosphinane 2-Oxide-d3, a deuterium labelledCyclophosphamide Impurity 4 (C984612),is a derivative ofCyclophosphamide Monohydrate (C988580), a known human carcinogen that is wide used in cancer chemotherapy because it can cross-link DNA causing strand breakage and mutation.